The development and evaluation of pressure-sensitive adhesive tapes for medical use, e.g. so-called medical adhesives such as would be employed to hold a wound dressing in place, involve complex issues in adhesion to skin and related testing procedures.
Although human test panels will of course provide in vivo data, these test procedures are costly and difficult, and are characterized by large variability in such factors as surface morphology, presence of surface moisture and sebum, etc. Moreover, protocol for human testing requires screening for pregnancy, medical problems including any which may be affected by transdermal diffusion of trace amounts of unreacted monomer which may be present in the adhesive formulation, filling out and signing consent forms, liability issues and the like.
On the other hand, in vitro methods using excised human skin and animal models are also highly variable, tedious and preparation intensive. Other test substrates, such as steel and glass, offer ease and precision in laboratory testing, but the test results are not easily correlated to the results obtainable in the contemplated use on actual skin surfaces.
For these reasons, it has heretofore been suggested that in vitro testing be done on smooth polyamide surfaces of collagen and 66-nylon. (See, for example, Komerska, J. F. and Moffett, N., Proceedings of Pressure Sensitive Tape Council, 108 (1985); Schott, H., J. Pharm. Sci., 60, 1894 (1971). However, these materials are inadequate for analytical comparison with the dispersive and polar intermolecular properties of human skin. Moreover, they do not account for the topographical aspects, including variations thereof, in human skin.
In view of the foregoing discussion it will be appreciated that there is a great need by manufacturers of medical adhesives and tapes, as well as other investigators of their application to the skin, for inexpensive, reproducible test surfaces whose properties substantially correlate to or reflect those of human skin.